Characterization of a C-terminal fragment of the recombinant STAT1 protein by MALDI-MS. Determination of the extent of alkylation as well as phosphorylation of the protein. Continuation of this project will include the determination of amino acid residues that are important for DNA binding using photocrosslinking and MALDI-MS peptide mapping. A paper describing this work has been published U. Vinkemeier, S.L. Cohen. I. Moarefi, B.T. Chait, J. Kuriyan & J.E. Darnell "DNA binding of in vitro activated Stat1(, Stat1( and truncated Stat1 interaction between NH2-terminal domains stabilizes binding of two dimers to tandem DNA sites." EMBO J. 15 (1996) 5616 - 5626.